1. Field of the Invention
The present invention relates to flame-protected impact-modified polycarbonate compositions which comprise a graft polymer containing a silicone-acrylate composite rubber and an oligophosphate based on bisphenol A and which are free of rubber-free polyalkyl (alkyl)acrylate, to the use of the polycarbonate compositions in the production of moulded bodies, and to the moulded bodies themselves.
2. Description of Related Art
WO-A 2004/069914 discloses flame-resistant polycarbonate compositions which comprise polyalkyl (alkyl)acrylate and halogen-free oligophosphates and which are free of polymers whose synthesis involves butadiene, styrene or acrylonitrile. The compositions are distinguished by good joint line strength, resistance to chemicals, dimensional stability under heat, elongation at tear and flowability. The compositions of the present invention differ from the compositions according to WO-A 2004/069914 in that the compositions according to the invention do not contain rubber-free polyalkyl (alkyl)acrylate.
WO-A 2002/046305 discloses impact-modified, flame-resistant polycarbonate compositions comprising polycarbonate, impact modifier, phosphorus-containing flameproofing agents. The compositions are distinguished by improved notched impact strength in the low-temperature range. WO-A 2002/046305 does not, however, disclose compositions containing an impact modifier having a graft base of silicone-acrylate composite rubber.
EP-A 635547 discloses flame-protected polycarbonate compositions comprising polycarbonate, a copolymer gel, an impact modifier based on acrylate or diene rubber, a flameproofing agent such as, for example, oligophosphate, and optionally an impact modifier having a graft base of diene rubber, acrylate rubber or EPDM rubber. EP-A 635547 does not, however, disclose compositions containing an impact modifier having a graft base of silicone-acrylate composite rubber.
U.S. Pat. No. 6,423,766 discloses flame-protected polycarbonate compositions having an impact modifier which has a graft base of silicone-acrylate composite rubber, wherein the weight ratio of impact modifier to phosphorus from the phosphoric acid ester is from 2 to 15. The compositions have improved mechanical properties and good processing behaviour. The compositions of the present invention differ from the compositions according to U.S. Pat. No. 6,423,766 in that the compositions according to the invention have a higher weight ratio of impact modifier to phosphorus from the phosphoric acid ester.